- Play on Easy or Normal at first, the difficulty ramps up pretty quick after the first couple stages.
- There is no auto-save. Make sure you save early and often.
- The game expects you to switch weapons regularly, otherwise you'll quickly start running into ammo problems.
- Maneuverability is life. Try to always have room to strafe and somewhere to retreat to.
- On that note, watch your step, the game is an asshole about bottomless pits.
- The shotgun has much less spread than you'd expect, but a fair bit of drift.
- Turning on or off objective hints is a personal choice, but mandatory objectives are hidden like secrets would be in another game.
- The free health/ammo refills at checkpoints are tied to that specific point. Don't feel bad about using them, but consider saving them if you think you might backtrack to them soon.
- Every level has one 'trap' checkpoint that takes you to a fairly tough arena fight, so try to keep that in mind. Bright side, find them all and you can assemble the ultimate weapon.
- Different versions of the game have their cheat codes changed for whatever reason, On the Steam/GOG release, the master cheat is BEWAREOBLIVIONISATHAND.
- You can play pseudo-co-op by entering multiplayer, then using the level warp cheat. Fair warning, this will completely disable checkpoints, so you may want to consider also turning on Infinite Ammo.